package tender_submission

import (
	"context"
	"errors"
	"strings"
	"tm/internal/tender"
	"tm/internal/tender_approval"
	"tm/pkg/logger"
	"tm/pkg/response"
)

// TenderApprovalReader verifies that a tender is approved before workflow actions.
type TenderApprovalReader interface {
	GetByTenderAndCompany(ctx context.Context, tenderID, companyID string) (*tender_approval.TenderApproval, error)
}

// Service defines tender submission business logic.
type Service interface {
	EnsureForApprovedTender(ctx context.Context, tenderID, companyID, customerID string) (*TenderSubmissionWithTenderResponse, error)
	GetByIDWithTender(ctx context.Context, id string) (*TenderSubmissionWithTenderResponse, error)
	GetByIDForCompanyWithTender(ctx context.Context, id, companyID string) (*TenderSubmissionWithTenderResponse, error)
	GetByTenderAndCompanyWithTender(ctx context.Context, tenderID, companyID string) (*TenderSubmissionWithTenderResponse, error)
	ListByCompanyWithTender(ctx context.Context, companyID string, form *ListTenderSubmissionsForm) (*TenderSubmissionListResponse, error)
	UpdateStatus(ctx context.Context, id string, form *UpdateSubmissionStatusForm, companyID, changedBy string) (*TenderSubmissionWithTenderResponse, error)
	GetCompanyStats(ctx context.Context, companyID string) (*CompanySubmissionStatsResponse, error)
	GetGlobalStats(ctx context.Context) (*AdminSubmissionStatsResponse, error)
	AdminListWithTender(ctx context.Context, form *ListTenderSubmissionsForm) (*TenderSubmissionListResponse, error)

	OnApprovalSubmitted(ctx context.Context, tenderID, companyID, customerID string) error
	OnApprovalRemoved(ctx context.Context, tenderID, companyID string) error
	OnApprovalRejected(ctx context.Context, tenderID, companyID, changedBy string) error
}

type tenderSubmissionService struct {
	repository       Repository
	approvalReader   TenderApprovalReader
	tenderService    tender.Service
	logger           logger.Logger
}

func NewService(repository Repository, approvalReader TenderApprovalReader, tenderService tender.Service, logger logger.Logger) Service {
	return &tenderSubmissionService{
		repository:     repository,
		approvalReader: approvalReader,
		tenderService:  tenderService,
		logger:         logger,
	}
}

func (s *tenderSubmissionService) EnsureForApprovedTender(ctx context.Context, tenderID, companyID, customerID string) (*TenderSubmissionWithTenderResponse, error) {
	resolvedTenderID, err := s.tenderService.ResolveMongoID(ctx, tenderID)
	if err != nil {
		s.logger.Warn("Failed to resolve tender for submission ensure", map[string]interface{}{
			"tender_ref": tenderID,
			"company_id": companyID,
			"error":      err.Error(),
		})
		return nil, ErrTenderNotFound
	}

	if err := s.requireSubmittedApproval(ctx, resolvedTenderID, companyID); err != nil {
		return nil, err
	}

	submission, err := s.repository.GetByTenderAndCompany(ctx, resolvedTenderID, companyID)
	if err != nil {
		if !errors.Is(err, ErrTenderSubmissionNotFound) {
			return nil, err
		}
		submission = NewTenderSubmission(resolvedTenderID, companyID, customerID)
		if err := s.repository.Create(ctx, submission); err != nil {
			if !errors.Is(err, ErrTenderSubmissionExists) {
				return nil, err
			}
			submission, err = s.repository.GetByTenderAndCompany(ctx, resolvedTenderID, companyID)
			if err != nil {
				return nil, err
			}
		}
	}

	return s.responseWithTender(ctx, submission, true)
}

func (s *tenderSubmissionService) GetByIDWithTender(ctx context.Context, id string) (*TenderSubmissionWithTenderResponse, error) {
	submission, err := s.repository.GetByID(ctx, id)
	if err != nil {
		return nil, err
	}
	return s.responseWithTender(ctx, submission, true)
}

func (s *tenderSubmissionService) GetByIDForCompanyWithTender(ctx context.Context, id, companyID string) (*TenderSubmissionWithTenderResponse, error) {
	submission, err := s.repository.GetByID(ctx, id)
	if err != nil {
		return nil, err
	}
	if submission.CompanyID != companyID {
		return nil, ErrTenderSubmissionNotFound
	}
	return s.responseWithTender(ctx, submission, true)
}

func (s *tenderSubmissionService) GetByTenderAndCompanyWithTender(ctx context.Context, tenderID, companyID string) (*TenderSubmissionWithTenderResponse, error) {
	resolvedTenderID, err := s.tenderService.ResolveMongoID(ctx, tenderID)
	if err != nil {
		return nil, ErrTenderNotFound
	}

	submission, err := s.repository.GetByTenderAndCompany(ctx, resolvedTenderID, companyID)
	if err != nil {
		return nil, err
	}
	return s.responseWithTender(ctx, submission, true)
}

func (s *tenderSubmissionService) ListByCompanyWithTender(ctx context.Context, companyID string, form *ListTenderSubmissionsForm) (*TenderSubmissionListResponse, error) {
	limit, offset, sortBy, sortOrder := listParams(form)
	statuses := parseStatuses(form.Status)
	stages := parseStages(form.Stage)

	submissions, total, err := s.repository.ListByCompany(ctx, companyID, statuses, stages, form.From, form.To, limit, offset, sortBy, sortOrder)
	if err != nil {
		s.logger.Error("Failed to list tender submissions", map[string]interface{}{
			"company_id": companyID,
			"error":      err.Error(),
		})
		return nil, errors.New("failed to list tender submissions")
	}

	return &TenderSubmissionListResponse{
		Submissions: s.enrichSubmissions(ctx, submissions, false),
		Metadata:    listMetadata(total, limit, offset),
	}, nil
}

func (s *tenderSubmissionService) AdminListWithTender(ctx context.Context, form *ListTenderSubmissionsForm) (*TenderSubmissionListResponse, error) {
	limit, offset, sortBy, sortOrder := listParams(form)
	statuses := parseStatuses(form.Status)
	stages := parseStages(form.Stage)

	submissions, total, err := s.repository.Search(ctx, form.TenderID, form.CompanyID, statuses, stages, form.From, form.To, limit, offset, sortBy, sortOrder)
	if err != nil {
		s.logger.Error("Failed to admin list tender submissions", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("failed to list tender submissions")
	}

	return &TenderSubmissionListResponse{
		Submissions: s.enrichSubmissions(ctx, submissions, false),
		Metadata:    listMetadata(total, limit, offset),
	}, nil
}

func (s *tenderSubmissionService) UpdateStatus(ctx context.Context, id string, form *UpdateSubmissionStatusForm, companyID, changedBy string) (*TenderSubmissionWithTenderResponse, error) {
	s.logger.Info("Updating tender submission status", map[string]interface{}{
		"submission_id": id,
		"company_id":    companyID,
		"new_status":    form.Status,
		"changed_by":    changedBy,
	})

	submission, err := s.repository.GetByID(ctx, id)
	if err != nil {
		return nil, err
	}

	if companyID != "" && submission.CompanyID != companyID {
		return nil, ErrTenderSubmissionNotFound
	}

	expectedUpdatedAt := submission.UpdatedAt
	if err := s.validateStatusTransition(submission.Status, form.Status); err != nil {
		s.logger.Error("Invalid tender submission status transition", map[string]interface{}{
			"submission_id":  id,
			"current_status": submission.Status,
			"new_status":     form.Status,
			"error":          err.Error(),
		})
		return nil, err
	}

	submission.AddStatusChange(form.Status, form.Reason, changedBy, form.Description)
	if err := s.repository.UpdateIfUpdatedAt(ctx, submission, expectedUpdatedAt); err != nil {
		if errors.Is(err, ErrConcurrentUpdate) {
			return nil, ErrConcurrentUpdate
		}
		return nil, errors.New("failed to update tender submission status")
	}

	s.logger.Info("Tender submission status updated", map[string]interface{}{
		"submission_id": id,
		"status":        submission.Status,
		"stage":         submission.Stage,
	})

	return s.responseWithTender(ctx, submission, true)
}

func (s *tenderSubmissionService) GetCompanyStats(ctx context.Context, companyID string) (*CompanySubmissionStatsResponse, error) {
	stats, err := s.repository.GetCompanyStats(ctx, companyID)
	if err != nil {
		s.logger.Error("Failed to get company submission stats", map[string]interface{}{
			"company_id": companyID,
			"error":      err.Error(),
		})
		return nil, errors.New("failed to get submission statistics")
	}
	return stats, nil
}

func (s *tenderSubmissionService) GetGlobalStats(ctx context.Context) (*AdminSubmissionStatsResponse, error) {
	stats, err := s.repository.GetGlobalStats(ctx)
	if err != nil {
		s.logger.Error("Failed to get global submission stats", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("failed to get submission statistics")
	}
	return stats, nil
}

func (s *tenderSubmissionService) OnApprovalSubmitted(ctx context.Context, tenderID, companyID, customerID string) error {
	existing, err := s.repository.GetByTenderAndCompany(ctx, tenderID, companyID)
	if err != nil && !errors.Is(err, ErrTenderSubmissionNotFound) {
		return err
	}
	if existing != nil {
		if IsTerminalStatus(existing.Status) {
			existing.ReopenForApproval(customerID, "Tender re-approved")
			return s.repository.Update(ctx, existing)
		}
		return nil
	}

	submission := NewTenderSubmission(tenderID, companyID, customerID)
	if err := s.repository.Create(ctx, submission); err != nil {
		if errors.Is(err, ErrTenderSubmissionExists) {
			existing, getErr := s.repository.GetByTenderAndCompany(ctx, tenderID, companyID)
			if getErr != nil {
				return getErr
			}
			if IsTerminalStatus(existing.Status) {
				existing.ReopenForApproval(customerID, "Tender re-approved")
				return s.repository.Update(ctx, existing)
			}
			return nil
		}
		s.logger.Error("Failed to create submission on approval", map[string]interface{}{
			"tender_id":  tenderID,
			"company_id": companyID,
			"error":      err.Error(),
		})
		return err
	}

	s.logger.Info("Submission workflow created from approval", map[string]interface{}{
		"tender_id":  tenderID,
		"company_id": companyID,
	})
	return nil
}

func (s *tenderSubmissionService) OnApprovalRemoved(ctx context.Context, tenderID, companyID string) error {
	submission, err := s.repository.GetByTenderAndCompany(ctx, tenderID, companyID)
	if err != nil {
		if errors.Is(err, ErrTenderSubmissionNotFound) {
			return nil
		}
		return err
	}

	if submission.Status != StatusOpportunity {
		return nil
	}

	if err := s.repository.Delete(ctx, submission.GetID()); err != nil {
		s.logger.Error("Failed to remove opportunity submission after approval toggle", map[string]interface{}{
			"submission_id": submission.GetID(),
			"error":         err.Error(),
		})
		return err
	}
	return nil
}

func (s *tenderSubmissionService) OnApprovalRejected(ctx context.Context, tenderID, companyID, changedBy string) error {
	submission, err := s.repository.GetByTenderAndCompany(ctx, tenderID, companyID)
	if err != nil {
		if errors.Is(err, ErrTenderSubmissionNotFound) {
			return nil
		}
		return err
	}

	if IsTerminalStatus(submission.Status) {
		return nil
	}

	if err := s.transitionSubmission(submission, StatusNotApplied, "approval_rejected", changedBy, "Tender approval was rejected"); err != nil {
		var transitionErr *InvalidStatusTransitionError
		if errors.Is(err, ErrTerminalStatus) || errors.As(err, &transitionErr) {
			s.logger.Warn("Skipping approval rejection sync due to invalid transition", map[string]interface{}{
				"tender_id":      tenderID,
				"company_id":     companyID,
				"current_status": submission.Status,
				"target_status":  StatusNotApplied,
			})
			return nil
		}
		return err
	}
	return s.repository.Update(ctx, submission)
}

func (s *tenderSubmissionService) transitionSubmission(submission *TenderSubmission, next SubmissionStatus, reason, changedBy, description string) error {
	if err := s.validateStatusTransition(submission.Status, next); err != nil {
		return err
	}
	submission.AddStatusChange(next, reason, changedBy, description)
	return nil
}

func (s *tenderSubmissionService) requireSubmittedApproval(ctx context.Context, tenderID, companyID string) error {
	approval, err := s.approvalReader.GetByTenderAndCompany(ctx, tenderID, companyID)
	if err != nil {
		if errors.Is(err, tender_approval.ErrTenderApprovalNotFound) {
			return ErrApprovalRequired
		}
		return err
	}
	if approval.Status != tender_approval.ApprovalStatusSubmitted {
		return ErrApprovalRequired
	}
	return nil
}

func (s *tenderSubmissionService) validateStatusTransition(current, next SubmissionStatus) error {
	if IsTerminalStatus(current) {
		return ErrTerminalStatus
	}

	for _, allowed := range AllowedNextStatuses(current) {
		if allowed == next {
			return nil
		}
	}

	allowed := AllowedNextStatuses(current)
	allowedStrings := make([]string, len(allowed))
	for i, status := range allowed {
		allowedStrings[i] = string(status)
	}
	return NewInvalidStatusTransitionError(string(current), string(next), allowedStrings)
}

func (s *tenderSubmissionService) responseWithTender(ctx context.Context, submission *TenderSubmission, fullDetails bool) (*TenderSubmissionWithTenderResponse, error) {
	tenderResp, err := s.tenderService.GetByID(ctx, submission.TenderID, "")
	if err != nil {
		s.logger.Warn("Failed to load tender for submission response", map[string]interface{}{
			"tender_id": submission.TenderID,
			"error":     err.Error(),
		})
		return submission.ToResponseWithTender(nil), nil
	}

	var details *TenderDetails
	if fullDetails {
		details = fullTenderDetailsFromResponse(tenderResp)
	} else {
		details = listTenderDetailsFromResponse(tenderResp)
	}
	return submission.ToResponseWithTender(details), nil
}

func listParams(form *ListTenderSubmissionsForm) (limit, offset int, sortBy, sortOrder string) {
	limit = 20
	offset = 0
	sortBy = "updated_at"
	sortOrder = "desc"

	if form == nil {
		return limit, offset, sortBy, sortOrder
	}
	if form.Limit != nil && *form.Limit > 0 {
		limit = *form.Limit
	}
	if limit > maxListLimit {
		limit = maxListLimit
	}
	if form.Offset != nil && *form.Offset >= 0 {
		offset = *form.Offset
	}
	if form.SortBy != nil && strings.TrimSpace(*form.SortBy) != "" {
		sortBy = strings.TrimSpace(*form.SortBy)
	}
	if form.SortOrder != nil && strings.TrimSpace(*form.SortOrder) != "" {
		sortOrder = strings.TrimSpace(*form.SortOrder)
	}
	return limit, offset, sortBy, sortOrder
}

func parseStatuses(values []string) []SubmissionStatus {
	if len(values) == 0 {
		return nil
	}
	out := make([]SubmissionStatus, 0, len(values))
	for _, value := range values {
		value = strings.TrimSpace(value)
		if value == "" {
			continue
		}
		out = append(out, SubmissionStatus(value))
	}
	return out
}

func parseStages(values []string) []SubmissionStage {
	if len(values) == 0 {
		return nil
	}
	out := make([]SubmissionStage, 0, len(values))
	for _, value := range values {
		value = strings.TrimSpace(value)
		if value == "" {
			continue
		}
		out = append(out, SubmissionStage(value))
	}
	return out
}

func listMetadata(total int64, limit, offset int) *response.Meta {
	pages := int(total) / limit
	if limit > 0 && int(total)%limit > 0 {
		pages++
	}
	page := 1
	if limit > 0 {
		page = (offset / limit) + 1
	}
	return &response.Meta{
		Total:  int(total),
		Limit:  limit,
		Offset: offset,
		Page:   page,
		Pages:  pages,
	}
}